2lS 



HARDWICKE'S SCIENCE-GOSSIP. 



observer and distinguished naturalist detected between 

 the Pollan of Lough Neagh and other somewhat 

 similar fish met with elsewhere in the south and west 

 of Ireland, would seem to have led him to designate 

 the former a distinct species. It may here be observed 

 that species of fish allied to, if not identical with, 

 those inhabiting the sea, have been discovered in 

 other European lakes, and under conditions some- 

 what similar to those observed by the Duke of Argyll, 

 attending the occupants of the Italian lakes. It is, 

 however, unnecessary here to pursue the subject 

 further than to point out the singular coincidence 

 between Lough Neagh and the latter. I am induced 

 to make this attempt very much in consequence of 

 the observation which follows in the Duke's paper. 



"Every case," his Grace remarks, "in which 

 fish now confined to fresh waters, whether fluvial or 

 lacustrine, can be identified as a species with what 

 has been marine, is of the highest interest in a 

 zoological and geological point of view." The close 

 resemblance between the lacustrine species of the 

 Italian lakes and the Pollan of Lough Neagh has 

 already been noticed. It now remains that the 

 geological features of the latter be reviewed. 



Lough Neagh, the most extensive lake in the 

 British Islands, or as indeed it might be termed an 

 inland sea, occupies a nearly central position in the 

 vast area of the volcanic beds, or sheets of lava, once 

 extending over a surface of about 1200 miles, iden- 

 tical with the entire county of Antrim, together with 

 portions of Londonderry and Tyrone, and reappear- 

 ing in the Scottish Hebrides and Faroe Islands. 

 Geologists of the highest eminence, in tracing the 

 history of this enormous overflow of molten lava, 

 have assigned it to several periods, including three 

 stages : the first during the later Eocene, the second 

 during the Miocene, and the latest coetaneous with 

 the still later portion of the Miocene, and charac- 

 terised, according to Professor Hull, " by more solid 

 sheets of basalt and numerous vertical dykes." 



It may readily be conceived that an enormous 

 lapse of duration must have intervened between the 

 earliest and the latest periods of this exercise of 

 volcanic energy. At a later stage of the process, as 

 Professor Hull observes: "The country was sub- 

 merged beneath the waters of the inter-glacial sea, 

 which deposited the sands and gravels which overlie 

 the lower boulder clay ; and subsequent emergences 

 during the stage of the upper boulder clay, together 

 with atmospheric agencies, constantly at work, the 

 newer land has been exposed, have moulded the 

 surface into the form which we now behold." 



This volcanic action has written its history in the 

 escarpments of the basaltic plateau, which reveal the 

 beds of new red marls, lias, chalk, the basaltic sheets 

 of the Miocene age, and the raised beaches dis- 

 cernible on the shores of Lough Neagh. 



The agency of water is discoverable over the vast 

 area, plainly indicating that the waters of the Northern 



Sea once covered the whole. The action of rivers 

 which have disappeared has been traced here, one 

 of which has, with much probability, been connected 

 with another, the bed of which has been discovered 

 under the Scaur of Eigg, one of the Hebrides, wherein 

 have been found fragments of the silicified wood for 

 which Lough Neagh has long been remarkable. 



May it not, in such a state of things, be readily 

 conceived that amidst the upheaving of earthquakes, 

 while the masses of basalt were forced upwards, and 

 the floods of lava were poured successively over the 

 plateau above indicated, and when vast subsidence 

 occurred where Lough Neagh now appears, that 

 which was then a marine sheet of water assumed the 

 lacustrine form which it now presents, and that along 

 with it were included shoals of herrings, which by 

 the adaptive power of nature now survive as the 

 Pollan of Lough Neagh ? 



Experts and adepts in geological fauna will be 

 better qualified to pronounce on the feasibility of the 

 above hypothesis. It appears, however, to the writer 

 to accord in a very remarkable manner with the ob- 

 servations of the Duke of Argyll on the species of 

 fish which are found in the Italian lakes, as well as 

 with the geological theory to which their occurrence 

 therein has given rise, and which is alluded to in his 

 Grace's valuable paper. 



WILD FLOWERS AND THEIR NAMES. 



AS F. H. Hn. asks for information as to the best 

 means of discovering the names of flowers, 

 perhaps the following remarks may be of some slight 

 use to him. Any one who has not reached a state of 

 scientific petrifaction, will admit that there are many 

 ways of attaining this object, each possessing its 

 special advantages. What is the best method in any 

 case depends on the amount of knowledge of which 

 the inquirer is master. For children, and those who 

 know nothing of botany, the simplest plan is, of 

 course, to compare the plant with a coloured illustra- 

 tion, such as those contained in Pratt's "Wild 

 Flowers," published by the Society for Promoting 

 Christian Knowledge at i6j. The next simplest 

 plan is to use artificial keys. Those in Bentham's 

 handbook are excellent, and the edition without 

 illustrations is published at \2s. The illustrations 

 may be had separately. There is an advantage in 

 this, as the species can first be determined without 

 the help of the illustrations, the use of which many 

 consider unscientific, and the result may be afterwards 

 checked by their aid. After a little practice the 

 tedious process may be shortened, by referring at 

 once to the key to the genera of the order, or even to 

 the key to the species of the genus to which the plant 

 belongs. It is in the completeness of the keys that 

 the superiority of Bentham chiefly consists. The 

 Linncean system is in fact an artificial key. Hardly 

 any " Floras" are now arranged in accordance with 



